Question:
Find the radius of gyration of a circular ring of radius $r$ about a line perpendicular to the plane of the ring passing through one of its particles.
Solution:
.$I_{a x i s}=I_{C O M}+m x^{2}$
$I_{A A^{r}}=m r^{2}+m r^{2}$
$I_{A A^{r}}=2 m r^{2}$
$\mathrm{~m}^{k^{2}}=2 m r^{2}$
$\therefore \mathrm{k}=\sqrt{2} r$